Primary immunodeficiency diseases arise due to genetic abnormalities of one or more genes important in human immunity. While these diseases are present in all populations, there is a noticeable lack of minority subjects in published studies; we suggest this results from under-diagnosis. Delayed diagnosis leads to increased morbidity and inflated global medical costs; in many cases delay results in increased mortality. In addition, in case of bio-terrorist activity, these un-diagnosed subjects could not be given adequate protection. The hypothesis of this ongoing demonstration and education program (R18) is that these patients can be identified in a multi-racial urban hospital population, using a newly devised computer scoring program to surveying hospital discharge diagnoses using international disease codes for illnesses commonly associated with congenital immune deficiency. Surveying diagnoses of inpatients over 5 years, 0.4% of all patients have had two or more significant illnesses suggestive of immunodeficiency without other diagnoses leading to these conditions. These patients were significantly younger, sicker, more often Hispanic, and more likely to have Medicaid than patients without these codes (p=.001); this group was admitted between 1 and 30 times, an average of 5 admissions for each. The commonest diagnoses were pneumonia, sepsis, failure to thrive, empyema, and bronchiectasis and osteomyelitis. Of 48 tested subjects of the 235 patients with more illnesses, 17 have primary immune deficiency (35%) and 4 others have secondary defects; 13/17 are Hispanic. We will continue to test patients found by computer screening, to verify if immune deficiency is present. A second goal is to validate the computer scoring method against a large and growing number of doctor-referred patients (now 250 subjects since 2000) with proven primary immune deficiency and to define disease code clusters that better identify individual defects. A third goal is to create a portable version of computer screening that can be applied more widely, as for example in the city hospitals of NYC, medical data bases, and other test populations. A final goal is to continue to implement our program of community-based provider outreach and education (Study Targeting Recognition of Immune Deficiency and Evaluation, STRIDE) and to involve the affiliated medical facilities that will most benefit from the educational services, diagnostic and treatment resources pertinent to congenital immune defects.